An official inquiry into Britain's involvement in the Iraq War begins

LONDON (Reuters) - An official inquiry into Britain's involvement in the Iraq War begins on Tuesday, promising a thorough investigation which could prove embarrassing for the government ahead of next year's election.

The five-member inquiry team, headed by former civil servant John Chilcot, was set up by Prime Minister Gordon Brown in June to examine the reasons for Britain's involvement in the 2003 U.S.-led invasion and the subsequent occupation of Iraq.

Former Prime Minister Tony Blair sent over 45,000 troops to topple Saddam Hussein in a war that became deeply unpopular in Britain and angered many supporters of the Labour government.

The country's combat operations officially ended at the end of April this year, six years after the invasion and with the deaths of 179 British service personnel.

Relatives of some of those killed and opposition politicians have long called for an inquiry into the war, arguing the government had distorted intelligence to justify the invasion.

A government dossier justifying military action included the claim that Saddam was capable of launching weapons of mass destruction within 45 minutes. No such weapons were found, leading to accusations the public had been deceived.

Commentators say evidence to the inquiry and publicly raking over such a divisive issue could embarrass the government before parliamentary elections which must be held by June 2010, with Brown already trailing in polls to the Conservatives.

However the inquiry's final verdict will not be made public until after the election, at the end of next year.

Chilcot's study will be the third official probe into the Iraq War. A 2004 inquiry into intelligence about Iraq's weapons of mass destruction concluded much of the information had been flawed but that ministers had not deliberately misled the public.

Another report earlier in 2004 cleared ministers of any wrongdoing over the death of an Iraq weapons expert who killed himself after the government outed him as the source of a BBC report that claimed Blair's team had "sexed up" intelligence.

Both findings were widely condemned in the media as being a whitewash, and fuelled demands for a full independent inquiry.

Chilcot said the investigation by his government-appointed panel aimed to avoid the criticism levelled at earlier probes.

"It won't be (a whitewash)," he said. "But the judgement as to whether people think it is will rely on how it's read when it comes out.

"We are completely determined to write the story fully and frankly on the basis of all the evidence we can get," he told the BBC.

Chilcot's team will begin by hearing testimony from senior officials and military officers. Blair and other politicians will be quizzed early next year, although Chilcot has not yet said whether Brown will be called to give evidence.